Origin

Late Middle English (in the sense 'lacking confidence or trust in someone or something'): from Latindiffident- 'failing in trust', from the verb diffidere, from dis- (expressing reversal) + fidere 'to trust'.

Both faith and fidelity (Late Middle English) come from the Latin word fides. Fido, a traditional name for a dog, is also related—it represents the Latin for ‘I trust’. Other words from the same source include confident (late 16th century), confide (Late Middle English), and diffident (Late Middle English) which originally meant ‘lacking in trust’. Fiancée, the French for ‘promised’, which goes back to fides is related. See also infidel